1. Field of the Invention
This invention relates to a novel process for producing an antibiotic KA-6643-A or a salt thereof.
2. Description of the Prior Art
The present inventors have found that a new strain KC-6643 belonging to the genus Streptomyces can prepare a novel antibiotic possessing potent antibacterial activity against gram-positive and gram-negative bacteria. As a result of this finding, they have succeeded in isolating antibiotics KA-6643-A and KA-6643-B as novel antibiotics from culture broths of such strain, as disclosed in co-pending United States patent application Ser. No. 137,259 in the names of the present inventors and other joint inventors.
In general, these novel antibiotics are represented by the formula (III): ##STR3##
The formula (III) represents the KA-6643-A antibiotic when R is a hydrogen atom and the KA-6643-B antibiotic when R is a sulfonic acid group. Both the KA-6643-A antibiotic (hereinafter referred to as "KA-6643-A") and the KA-6643-B antibiotic (hereinafter referred to as "KA-6643-B") exhibit marked antibacterial potency. It has been found that the former is superior in the potency to the latter.
In various studies leading to the present invention, it has now been found that KA-6643-A can be easily obtained from conversion of KA-6643-B by hydrolysis.